Definition
VS is the stalling speed, or the minimum steady flight speed at which the airplane remains controllable. It represents the slowest speed at which the wing can still produce enough lift to support the airplane in flight before the airflow separates and the wing stalls. VS is published in the Pilot's Operating Handbook and is the baseline speed from which other V-speeds (such as VS0 and VS1) are derived.
Plain English
VS is the slowest speed at which the airplane can still fly under control. Below this speed, the wing stops producing enough lift and the airplane stalls.
Context Anchor
In a VMC demonstration, pilots watch for stall warning signs and recover before allowing the airplane to reach a full stall.
Derivation
The 'V' comes from the French 'vitesse,' meaning speed. The subscript 'S' stands for 'stall.' So VS literally reads as 'speed — stall,' the speed at which the airplane stalls.
Why Pilots Care
Knowing VS helps pilots maintain safe margins above stall during engine-out maneuvers to prevent loss of control.
Grounding Statement
At stalling speed the smooth airflow over the wing breaks away, causing a sudden loss of lift.
Intuition Check
Do not think of stalling speed as one fixed speed that is always the same. VS applies under specified conditions, and the actual stall can occur at different speeds if weight, bank, loading, or airplane configuration changes.
Example Sentence 1
During the VMC demonstration, the instructor briefed that recovery must begin at the first sign of a stall or before reaching VS, whichever occurs first.
Example Sentence 2
The published VS for the aircraft was 58 knots in the landing configuration.